(a) Field of the Invention
The present invention relates to an active material for a rechargeable lithium battery, and a rechargeable lithium battery including the same and more particularly, the present invention relates to an active material for a rechargeable lithium battery having excellent high rate characteristics and/or cycle-life characteristics, and including the same.
(b) Description of the Related Art
In recent times, due to due to reductions in size and weight of portable electronic equipment in accordance with developments in the electronics industries, such portable electronic equipment has increasingly been used. A battery having a high energy density for a power source of such a portable electronic equipment is needed and thus research into rechargeable lithium batteries has been actively made.
For a positive active material of a rechargeable lithium battery, lithium-transition element oxides have been used, and for a negative active material, carbon-based active materials, silicon, tin, or alloys alloyed with other metals have been used.
The above non-carbon-based active materials such as lithium-transition elements oxide, or silicon, tin or alloys require a carbon-based conductive material to provide a high-Capacity battery due to their low electronic conductivity.
For the conductive material, carbon-based conductive materials such as conductive carbon black have generally been used.
Particularly, carbon black in the form of very small nano-beads is agglomerated and has a large specific area and has generally been used for the conductive materials. However, carbon black is an electrostatic agglomerate of nano beads and therefore when interfaces between active material particles are large in accordance with electrode expansion during long cycles of charge and discharge, the agglomerate of carbon black particles may easily be separated and the conductive paths decrease, causing resistance in a battery and resulting in reduction of cycle-life. The conductive material has a sufficient contact with active material particles, and therefore, an increased amount of the conductive material is required.